Physical Characteristics of Knitted Polyester Vascular Prostheses： Can the Wall Be Considered as a Scaffold for Tissue Regeneration？

Recent developments in endovascular surgery (EVAR) have opened new avenues to successfully treat aneurysms with percutaneous deployment of stent-grafts.Manufacturers have preferred to use woven fabrics or micro-porous tubes which are supported by metallic frames or stents.Woven fabrics are much thinner than knits and this permits the use of a smaller delivery catheter.However,since woven constructions are stiffer and have little porosity,the tissue ingrowth is poor or absent.On the other hand,knitted constructions can be considered as a scaffold for tissue ingrowth,and hence they represent an attractive alternative because of their open structure and better conformability in the case of balloon deployment.The present study was undertaken to analyze the properties of two knitted and crimped polyester arterial prototype prostheses,one with and the other without a gelatin coating as sealant.Two commercial controls were also included in the study,namely the uncoated knitted polyester vascular prosthesis VP1200K,and its sealed version,the gelatin coated polyester knitted Gelsoft device,manufactured by Vascutek Ltd.,Scotland,UK.In vitro testing consisted of analyzing the geometry and morphology of the yarn and fabric structures,and measuring the physical and mechanical properties of the grafts,including the water permeability,the longitudinal and radial compliance,and the suture retention strength.In order to compare the different properties of the four samples,tests were also performed on the gelatin coated or sealed devices before and after gelatin removal.The results provided a useful comparison between the prototypes and the commercial control devices.The latter used ten times the amount of gelatin which had been applied as a coating in order to achieve the same low level of impermeability to water.The different amounts of gelatin also explained the different mechanical performance,such as compliance,for these prototype and control prostheses.

Physical Characteristics of Knitted Polyester Vascular Prostheses： Can the Wall Be Considered as a Scaffold for Tissue Regeneration？

Recent developments in endovascular surgery (EVAR) have opened new avenues to successfully treat aneurysms with percutaneous deployment of stent-grafts. Manufacturers have preferred to use woven fabrics or microporous tubes which are supported by metallic frames or stents. Woven fabrics are much thinner than knits and this permits the use of a smaller delivery catheter. However, since woven constructions are stiffer and have little porosity, the tissue ingrowth is poor or absent. On the other hand knitted constructions can be considered as a scaffold for tissue ingrowth, and hence they represent an attractive alternative because of their open structure and better conformability in the case of balloon deployment. The present study was undertaken to analyze the properties of two knitted and crimped polyester arterial prototype prostheses, one with and the other without a gelatin coating as sealant. Two commercial controls were also included in the study, namely the uncoated knitted polyester vascular prosthesis VP1200K, and its sealed version, the gelatin coated polyester knitted Gelsoft device,manufactured by Vascutek Ltd., Scotland, UK. In vitro testing consisted of analyzing the geometry and morphology of the yarn and fabric structutres, and measuring the physical and mechanical properties of the grafts, including the water permeability, the longitudinal and compliance, and the suture retention strength. In order to compare the different properties of the four samples, tests were also performed on the gelatin crated or sealed devices before and after gelatin removal. The results provided a useful comparison between the prototypes and the commercial control devices. The latter used tea times the amount of gelatin which had been applied as a coating in order to achieve the same low level of impermeability to water. The different amounts of gelatin also explained the different mechanical performance such as compliance, for these prototype and control prostheses.